With a pod after the combination of Trafalgar, the Peninsula War and 1812 in Russia, consider a scenario when the French fleet fights out and receives its 'Waterloo' or a second Trafalgar. Add Spanish and Russian ships to the British side if needed. [Move it to another forum such as asb if needed or suggest a more plausible p.o.d..]
P.O.D.:
After the return of Napoleon in 1815 to France, the Emperor was contemplating his war plans when he realised the strength of the coalition against him and British funding. The French emperor suddenly considered the option of his navy attacking the British and suggested that the French Mediterranean Fleet sortie from Toulon to disrupt British trade in the Mediterranean and the blockade of the Atlantic.
Under political pressure, the French Navy under Admiral Allemand sortied on 8 June 1815 and headed into the Atlantic from Brest and Rochefort. The orders for the French Navy in the Mediterranean were received by Admiral Cosmao, who sortied a week earlier.
Now, the outcome must be familiar if they met the blockading Royal Navy squadrons, with a decisive French defeat. But is this possible? [Planning starting shortly after 19 March 1815.] Maybe have Napoleon win Waterloo before being defeated later.
If possible, my scenario will be posted tomorrow.